Dinosaurs Fell Victim to “Perfect Storm” of Events, Study Infers

Dinosaurs might have survived the asteroid strike that wiped them out if it had taken place slightly earlier or later in time, according to new research conducted in part by the American Museum of Natural History. The study, published today in Biological Reviews, builds a new narrative of the prehistoric creatures’ demise some 66 million years ago when a six-mile- (10-kilometer-) wide asteroid struck what is now Mexico.

Triceratops, an herbivore common in the Maastrichtian stage.

“The dinosaurs were victims of colossal bad luck,” said lead author Steve Brusatte, a researcher at the University of Edinburgh’s School of GeoSciences. “Not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable. Our new findings help clarify one of the enduring mysteries of science.”

The international team of scientists, which included the Museum’s Paleontology Division Chair Mark Norell, who was Brusatte’s Ph.D. advisor, studied an updated catalog of dinosaur fossils to create a picture of how dinosaurs changed over the few million years before the asteroid hit. They found that Earth was experiencing environmental upheaval, including extensive volcanic activity, changing sea levels, and varying temperatures.

At this time, the dinosaurs’ food chain was weakened by a lack of diversity among the large plant-eating dinosaurs on which others preyed, probably because of changes in the climate and environment, the researchers suggest.

The dinosaur-dominated fauna witnessed the asteroid impact at the end of the Cretaceous period about 66 million years ago and was replaced in the earliest Paleocene by a mammal-dominated fauna. This illustration shows representative members of major Campanian, Maastrichtian, and earliest Paleocene (Puercan) North American terrestrial vertebrates.

Image credit:Thomas Williamson, New Mexico Museum of Natural History and Science

This created a “perfect storm” in which dinosaurs were vulnerable and unlikely to survive the aftermath of the asteroid strike. That asteroid impact would have caused tsunamis, earthquakes, wildfires, sudden temperature changes, and other environmental changes. As food chains collapsed, the dinosaurs were wiped out, one species after another. The only dinosaurs to survive were those that could fly, from which modern birds descended.

The researchers suggest that if the asteroid had struck a few million years earlier, when the range of dinosaur species was more diverse and food chains were more robust, or later, when new species had time to diversify, then they very likely would have survived.

Ongoing studies in Spain and China could result in an even better understanding of what occurred during this time frame, more than 66 million years ago.